Generally, in 4 G communications systems, such as Third Generation Partnership Project (3GPP) Long Term Evolution (LTE) compliant communications systems, voice communications may be supported in the form of voice over Internet protocol (VoIP), wherein voice data is transmitted as a data packet. For example, a user equipment (UE), which may also be commonly referred to as a mobile station (MS), may use an adaptive multi-rate (AMR) speech coder and decoder (CODEC) to generate a voice frame containing voice data. The UE may subsequently add a real-time protocol (RTP) header, a user data protocol (UDP) header, and an Internet protocol (IP) header to the voice frame to form an IP packet. The UE then transmits the IP packet over an air interface to an enhanced NodeB (eNB), which may also be referred to as a base station (BS).
The AMR CODEC is a single integrated speech CODEC with multiple source bit-rates ranging from a low of 4.75 kbps to a high of 12.2 kbps, and a low rate Silence Descriptor (SID) encoding mode for background noise. The AMR CODEC is capable of switching its bit-rate every 20-msec upon command.
In a 3GPP LTE compliant communications system, an eNB provides transportation for data and signalling between the UE and a core network. The eNB also provides necessary control signalling to the UE in order to maintain radio communications. The eNB may become overloaded when traffic load increases, such as during busy hours of operation. The eNB may become overloaded with respect to its radio links, transport network, and/or due to hardware and/or software limitations in network equipment.
In order to alleviate the overload, the eNB may wish to reduce the data rate for UE communications. For example, the eNB may only grant new UE communications at low data rates, even if the granted data rates are lower than data rates requested by the UE. Furthermore, the eNB may cause existing UE communications to reduce their data rates.